It is common knowledge that a blade for ice skating will not turn unless it has a convex curvature along the bottom of the blade, called the radius, rock or rocker. It is further understood that a blade with more curved radius will turn more easily but glide less far.
Speed skate blade radius usually varies over the length of the blade, and is more curved at the toe and heel. Radius in the middle of the blade usually is more curved than the turn radius of the racing track.
Published material emphasizes the importance of having a convex speed skate blade radius in the range of six to nine meters when skating around a track with eight meters radius.
Speed skate racing is done with turns only in the counter-clockwise direction. Skate boots and blades for some events are adjusted to take advantage of this fact. Blades are mounted on boots with an offset to the left and some blades are positioned to the left in their support structure.
Blades of expert skaters are also bent to the left. Bending is done with mallet, vise or tool until the blade "looks right" or "feels right". The toe of the blade may be bent so the blade turns more sharply when a skater's weight moves forward. The heel of the blade may be bent so the blade turns more sharply when the skater's weight moves back. The whole blade may be bent in a smooth arc for increased ice contact and stability.
Published material treats bend as a matter of individual preference appropriate only for highly skilled skaters. Bend is considered separately from radius, and most skaters are actively discouraged from using bent blades.